This is a note to let you know that I've just added the patch titled
mptcp: prevent BPF accessing lowat from a subflow socket.
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mptcp-prevent-bpf-accessing-lowat-from-a-subflow-socket.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fcf4692fa39e86a590c14a4af2de704e1d20a3b5 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Fri, 29 Mar 2024 19:50:36 +0100
Subject: mptcp: prevent BPF accessing lowat from a subflow socket.
From: Paolo Abeni <pabeni@xxxxxxxxxx>
commit fcf4692fa39e86a590c14a4af2de704e1d20a3b5 upstream.
Alexei reported the following splat:
WARNING: CPU: 32 PID: 3276 at net/mptcp/subflow.c:1430 subflow_data_ready+0x147/0x1c0
Modules linked in: dummy bpf_testmod(O) [last unloaded: bpf_test_no_cfi(O)]
CPU: 32 PID: 3276 Comm: test_progs Tainted: GO 6.8.0-12873-g2c43c33bfd23
Call Trace:
<TASK>
mptcp_set_rcvlowat+0x79/0x1d0
sk_setsockopt+0x6c0/0x1540
__bpf_setsockopt+0x6f/0x90
bpf_sock_ops_setsockopt+0x3c/0x90
bpf_prog_509ce5db2c7f9981_bpf_test_sockopt_int+0xb4/0x11b
bpf_prog_dce07e362d941d2b_bpf_test_socket_sockopt+0x12b/0x132
bpf_prog_348c9b5faaf10092_skops_sockopt+0x954/0xe86
__cgroup_bpf_run_filter_sock_ops+0xbc/0x250
tcp_connect+0x879/0x1160
tcp_v6_connect+0x50c/0x870
mptcp_connect+0x129/0x280
__inet_stream_connect+0xce/0x370
inet_stream_connect+0x36/0x50
bpf_trampoline_6442491565+0x49/0xef
inet_stream_connect+0x5/0x50
__sys_connect+0x63/0x90
__x64_sys_connect+0x14/0x20
The root cause of the issue is that bpf allows accessing mptcp-level
proto_ops from a tcp subflow scope.
Fix the issue detecting the problematic call and preventing any action.
Reported-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/482
Fixes: 5684ab1a0eff ("mptcp: give rcvlowat some love")
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://lore.kernel.org/r/d8cb7d8476d66cb0812a6e29cd1e626869d9d53e.1711738080.git.pabeni@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mptcp/sockopt.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -1500,6 +1500,10 @@ int mptcp_set_rcvlowat(struct sock *sk,
struct mptcp_subflow_context *subflow;
int space, cap;
+ /* bpf can land here with a wrong sk type */
+ if (sk->sk_protocol == IPPROTO_TCP)
+ return -EINVAL;
+
if (sk->sk_userlocks & SOCK_RCVBUF_LOCK)
cap = sk->sk_rcvbuf >> 1;
else
Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are
queue-6.8/octeontx2-af-fix-pause-frame-configuration-in-gmp-mo.patch
queue-6.8/mptcp-prevent-bpf-accessing-lowat-from-a-subflow-socket.patch
queue-6.8/net-hns3-fix-index-limit-to-support-all-queue-stats.patch
queue-6.8/net-hns3-mark-unexcuted-loopback-test-result-as-unex.patch
queue-6.8/selftests-vxlan_mdb-fix-failures-with-old-libnet.patch
queue-6.8/inet-inet_defrag-prevent-sk-release-while-still-in-u.patch
queue-6.8/net-lan743x-add-set-rfe-read-fifo-threshold-for-pci1.patch
queue-6.8/net-bcmasp-bring-up-unimac-after-phy-link-up.patch
queue-6.8/net-hns3-fix-kernel-crash-when-devlink-reload-during.patch
